Double Clean seems to be a really good product (I've only used it once so far on some stained pub upholstery) but it shifted the dirt and left the fabric looking like new. I haven't tried it on carpets yet.
I did notice that it seems to produce more foam than the "Prochem Extraction Plus" that I had used previously but a defoamer sorted that out.
As a powder, it dissolves well in warm water something that I was a little concerned about.